# Customerio Rate Limits

> Implement Customer.io rate limiting and backoff. Use when handling high-volume API calls, implementing retry logic, or optimizing API usage. Trigger with phrases like "customer.io rate limit", "customer.io throttle", "customer.io 429", "customer.io backoff".

- Skill: `micsapp/customerio-rate-limits` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add micsapp/customerio-rate-limits`
- Raw SKILL.md: https://api.skillmd.com/api/skills/micsapp/customerio-rate-limits/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- License: MIT
- Author: micsapp (https://skillmd.com/u/micsapp)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/micsapp/customerio-rate-limits

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# Customer.io Rate Limits

## Overview
Understand and implement proper rate limiting and backoff strategies for Customer.io API to handle high-volume operations reliably.

## Rate Limit Details

### Track API Limits
| Endpoint | Limit | Window |
|----------|-------|--------|
| Identify | 100 requests/second | Per workspace |
| Track events | 100 requests/second | Per workspace |
| Batch operations | 100 requests/second | Per workspace |

### App API Limits
| Endpoint | Limit | Window |
|----------|-------|--------|
| Transactional email/push | 100/second | Per workspace |
| API queries | 10/second | Per workspace |

## Instructions

### Step 1: Implement Token Bucket Rate Limiter
Build a rate limiter with configurable tokens per second, automatic refill, and async waiting when tokens are depleted.

### Step 2: Add Exponential Backoff
Create retry logic with configurable max retries, base delay, max delay, and jitter factor. Skip retries on client errors (4xx except 429).

### Step 3: Create Rate-Limited Client
Wrap the Customer.io client to acquire a rate limit token before each request and apply backoff on failures.

### Step 4: Handle 429 Response Headers
Parse `X-RateLimit-Remaining`, `X-RateLimit-Reset`, and `Retry-After` headers to adapt dynamically.

### Step 5: Add Queue-Based Rate Limiting
Use p-queue with interval-based rate limiting for cleaner high-volume processing.

For detailed implementation code, load the reference guide:
`Read(${CLAUDE_SKILL_DIR}/references/implementation-guide.md)`

## Error Handling
| Scenario | Action |
|----------|--------|
| 429 received | Respect Retry-After header |
| Burst traffic | Use queue with concurrency limit |
| Sustained high volume | Implement sliding window |

## Resources
- [API Rate Limits](https://customer.io/docs/api/track/#section/Limits)
- [Best Practices](https://customer.io/docs/best-practices/)

## Next Steps
After implementing rate limits, proceed to `customerio-security-basics` for security best practices.

## Prerequisites

- Access to the API environment or API
- Required CLI tools installed and authenticated
- Familiarity with API concepts and terminology

## Output

- Configuration files or code changes applied to the project
- Validation report confirming correct implementation
- Summary of changes made and their rationale

See [API implementation details](${CLAUDE_SKILL_DIR}/references/implementation.md) for output format specifications.

## Examples

**Basic usage**: Apply customerio rate limits to a standard project setup with default configuration options.

**Advanced scenario**: Customize customerio rate limits for production environments with multiple constraints and team-specific requirements.